Postfix relay on opnsense for sending email port 587 from local email server?

[RamSense]

Hi,
I have my own email server running and I use postfix on opnsense as a mail gateway as described here:
https://docs.opnsense.org/manual/how-tos/mailgateway.html
This works great for port 25 SMTP to enable communication between the sending and receiving servers to my local hosted email server.

Now I wonder if opnsense-postfix can (and should?) also be used for port 587 (SMTP-STARTTLS), so that all email clients (pc, iphone, laptop, etc) can sent email by first going to port 587/postfix and sending emails from our local email server.

Currently I have port 25 pointing to and using postfix, while for port 587 and IMAP i use a port forward to the local email server. Can this be postfix also for the same reason of using port 25? And if so, how can I configure that using the postfix-GUI?

Thanks for explaining and help in advantage

[RamSense]

No Postfix users?
Or is there no use case for port 587 to go through postfix (plugin) as a mail gateway, since there is only a doc in opnsense about it for port 25?